I couldn't get the link to work on my computer but if this
is the shrug, it should be do-able. You could see if there is a smaller size and make that. More likely, you're going to have to make a swatch with your yarn and needles and see what gauge you get. Then translate the sts/inch you have into the number of sts needed for the dimensions of the shrug you want. The pattern may give you a schematic with inches written in to make this easier.